JP2016505484A - Liquid compounds and their use as hydrogen storage - Google Patents

Abstract

In accordance with the present invention, it is composed of only carbon and hydrogen elements, and is liquid at room temperature consisting of two or more compounds that constitute a mixture of synthetic substances that can be used as a heat transfer liquid in several known compositions. The mixture of comprises at least one compound having at least two non-condensed and non-pi-conjugated aromatic units and is used in a catalytic process for bonding hydrogen to or liberating hydrogen from the mixture. It is characterized by being.

Description

  The present invention relates to a liquid compound according to the preamble of the first claim and to its use as a hydrogen reservoir for supplying fuel to a consumer.

  The scenario currently being discussed for energy procurement from large-scale renewable sources, such as wind parks in the North Sea or Dezertec, is an essential and technical precondition, with as much loss of energy as possible. There is a need for suitable means to be able to store and transport. Otherwise, seasonal variations in production cannot be offset, otherwise efficient transport of effective energy over long distances cannot be realized.

  A particularly attractive means to accomplish the above challenges is the development of a new “energy carrier material” and the provision of technology for its efficient energy charging and release. The use of “energy-carrying material” means that energy procured in “energy-rich” locations at “energy-rich” time can be used, for example, to convert energy-deficient liquid A to energy-rich liquid B This is the starting point. B in this case can be stored for a long period of time without loss, and can be transported at a high energy density. The energy rich liquid B is returned to A again, releasing available energy where and when needed. A can be a liquid or gaseous substance. If both A and B are liquids, this concept offers the possibility of refilling A back to the place of energy generation.

A preferred approach to technically realize an energy transport system and energy storage system based on an “energy carrying material” is to form a material B rich in energy by filling hydrogen A in a material A with low energy. The hydrogen required here is preferably procured from the electrolysis of water using regeneratively generated electrical energy. This energy charging step is typically performed by catalytic hydrogenation under pressure according to the prior art. The energy release of substance B takes place by catalytic dehydrogenation at low pressure and high temperature. The hydrogen liberated at that time can be used as energy in, for example, a fuel cell or an internal combustion engine. When hydrogen is released in the vehicle, the hydrogen procured at that time can be directly used for operation of the vehicle. Examples known in the prior art include energy storage in the form of CH ₄ , NH ₃ , or methanol. In the hydrogen release of these compounds, gaseous substances CO ₂ are generated in the case of methane and methanol, or nitrogen is generated in the case of NH ₃ .

  DE 102008034221A1 (Patent Document 1) describes an alternative known concept in which form A, which is poor in energy, is a liquid, and thus a liquid is again obtained upon energy release. In this case, the energy-poor Form A can be stored and transported as a liquid for refilling with hydrogen at a time rich in energy and at a place rich in energy. Such a system is called a “liquid organic hydrogen carrier (LOHC)”. An example of such LOHC is disclosed in patent application EP 1475349A2.

  The LOHC system known in the prior art is preferably a material pair in which the low-energy material A is an aromatic compound that has a high boiling point, is functionalized, and is hydrogenated in the energy filling process. One particularly preferred example disclosed relates to the use of the N-ethylcarbazole / perhydro-N-ethylcarbazole material pair, where the energy charge is typically about 140 ° C. and elevated pressure, As well as energy release can be carried out at temperatures between 230-250 ° C. Perhydro-N-ethylcarbazole, a material rich in energy, has a hydrogen capacity of about 5.8% by weight of hydrogen in the system mentioned. Therefore, the energy stored in 100 kg of free hydrogen of perhydro-N-ethylcarbazole is sufficient to move the car about 500 km, in which only steam is used as a combustion product when using energy in the car. Not generated. This approach is therefore a technically interesting alternative to other energy storage concepts for mobile applications.

  According to the prior art, the reaction system for catalytically liberating hydrogen from liquid energy storage molecules consists of a solid state reactor or a slurry phase reactor. In addition, a reaction vessel capable of performing at least one function for hydrogen procurement and having a fixed pressure and temperature is provided, and the reaction vessel contains at least one object having a metallic support structure. A solid and highly porous coating on the support structure, the coating containing a substance that acts catalytically to liberate hydrogen from the liquid hydrogen-carrying compound. A reactor for releasing hydrogen from a liquid compound carrying hydrogen is under development. In this regard, it is advantageous that the liquid compound carrying hydrogen may be a mixture of a liquid compound carrying hydrogen (in a significant proportion) and other compounds.

  Many LOHC systems known in the prior art have heteroatom-carbon bonds. This structural feature activates the system for catalytic hydrogen release. However, the apparently higher nitrogen-carbon bond instability compared to carbon-carbon bonds or carbon-hydrogen bonds limits the thermal stability of all LOHC systems with nitrogen-carbon bonds to temperatures up to 280 ° C. It is also. Of course, even a slight pyrolysis phenomenon of the LOHC system is already serious for industrial applications. This is because this will adversely change the fixed point of the LOHC system as well as the packing and releasing properties by the catalyst. High thermal stability allows, among other things, reaction temperatures above 280 ° C. during catalytic hydrogen release, which leads to higher volumetric productivity of hydrogen release compared to lower temperatures.

DE102008034221A1 Patent application EP1475349A2

  The problem of the present invention is that it can be procured in large quantities and is composed only of carbon and hydrogen and is thermally stable above 280 ° C. It presents a liquid compound for use as a hydrogen reservoir that can be easily used in Further provided is a method for supplying hydrogen to a consumer using this liquid compound.

  The object of the invention is solved by the features of the first claim. Advantageous embodiments and variants and advantageous methods for supplying hydrogen to the consumer are the subject matter of the dependent claims.

  In accordance with the present invention, it is composed of only carbon and hydrogen elements, and is liquid at room temperature consisting of two or more compounds that constitute a mixture of synthetic substances that can be used as a heat transfer liquid in several known compositions. The mixture of comprises at least one compound having at least two non-condensed and non-pi-conjugated aromatic units and is used in a catalytic process for bonding hydrogen to or liberating hydrogen from the mixture. It is characterized by being.

  Using a mixture that is already used in a specific form in the hydrogen-poor form as a heat transfer oil, for example under the trade name Marlotherm LH or Marotherm SH (eg SASOL), as a liquid hydrogen storage and transport system, New and original. This is because the possibility of hydrogen filling of this mixture has not been taken into account everywhere before, and hydrogen filling allows new use by a free-running process. This is also true for the process of liberating hydrogen from the use of hydrogen-rich forms as previously unknown hydrogen carriers. This is because this mixture has a number of important and previously unforeseen advantages over the previously known liquid hydrogen storage and transport systems, i.e. it is inexpensive to introduce into the industry, It has high hydrogen capacity, low vapor pressure, high chemical and thermal stability, with known toxicity and ecotoxicity, well known and compatible with all packing and tank materials . By utilizing the heat transfer oil as the LOHC system, it is advantageous to avoid the disadvantageous behavior of the previously used LOHC system based on its limited thermal stability.

  An advantageous method for supplying hydrogen to the consumer at least according to the distribution using the mixture according to the invention is that the reactor is connected via an inlet line from the first storage tank for the mixture carrying hydrogen. The mixture fed and dehydrogenated in the reactor at high temperature and low pressure is led from the reactor to the second storage tank via the outlet pipe, where the reactor is connected via the connecting pipe. It is characterized by supplying hydrogen to the consumer. Such a method can be applied particularly advantageously when the consumer is an internal combustion engine or at least one fuel cell, in particular contributing to the energy supply of the vehicle. The first and second storage tanks can be connected to each other and may be connected to each other with the possibility that the contents of the storage tanks will mix.

  One preferred method according to the invention is that the mixture is contacted with a metal-containing catalyst in the reactor to bind or liberate hydrogen, with the metal-containing catalyst used for hydrogen filling and hydrogen release. The metal-containing catalyst used is the same or different solid catalyst, which solid catalyst comprises one or more of the metals palladium, nickel, platinum, iridium, ruthenium, cobalt, rhodium, copper, gold, rhenium or iron. It is characterized in that it is contained in a finely dispersed form on a porous, nonpolar carrier.

  All of the above methods are common in liberating hydrogen in a reactor from a mixture charged with hydrogen by catalytic dehydrogenation at high temperature and low pressure.

  The concept of heat-carrying oil carrying energy, which is applied here, is technically close to our previous energy supply by fossil energy carriers and therefore exists as a ship, refinery, gas station, etc. The advantage is that the existing infrastructure can be used. Among other things, the heat transfer oil that carries the energy can store excess energy from renewable production and can be coupled to energy demand and transportation for transportation, heating in today's infrastructure. This energy storage further has the following advantages: an almost unlimited, lossless storage capacity, high energy density, and low cost. Moreover, this energy store is suitable as a long-term store of energy and as a form of transport.

  Attempts to utilize commercially available heat conduction oils such as Marotherm LH or Marotherm SH (eg, SASOL) as the hydrogen release form of the LOHC system are based on the fact that the mixture forming the hydrogen storage and transport system is It is advantageous to contain compounds having at least two non-condensed aromatic units in a mass fraction of between 5% and 100%, preferably between 60 and 100%, particularly preferably between 90 and 100%. It showed that. Furthermore, it is advantageous if the mixture comprises more than 50%, preferably more than 90%, of different compounds containing all at least two uncondensed aromatic units. In that case, it is advantageous that one compound of the mixture forming the hydrogen storage and transport system can be the substance dibenzyltoluene in the hydrogen-poor form of this mixture. Further advantageous is when the mixture consists of more than 50%, preferably more than 90%, of different dibenzyltoluenes. This allows hydrogen-deficient forms to be converted to hydrogen-rich forms by occlusion of hydrogen through catalytic hydrogenation reactions, in which the charged hydrogen is at a mass fraction of at least 6%. The hydrogen pressure during the catalytic hydrogenation is between 5 and 200 bar, preferably between 10 and 100 bar, best between 30 and 80 bar. The reaction temperature for chemical hydrogenation is between 20 ° C. and 230 ° C., preferably between 50 ° C. and 200 ° C., but best between 100 and 180 ° C.

  Below, based on three figures, it describes and describes the general substance example of the heat conductor which can be advantageously used as a hydrogen carrier.

It is a figure based on Marlotherm LH (SASOL). It is a figure which shows Marlotherm SH (SASOL). FIG. 2 shows a comprehensive display of typical structural units in a mixture according to the invention.

  Marlotherm (eg SASOL) or similar industrially utilized heat transfer oils are mixtures of different isomers of benzyltoluene (Marlotherm LH, SASOL) and mixtures of different isomers of dibenzyltoluene (Marlotherm). SH, SASOL). These different isomers are formed by linking a benzyl group attached to the central toluene nucleus with the toluene nucleus at different ring positions relative to the methyl group of toluene. When allocating ring position 1 to the methyl group of the toluene nucleus, Marlotherm LH (SASOL) is a mixture of benzyltoluenes where the benzyl group is attached to the toluene nucleus at position 2, position 3, or position 4. That is, in FIG. 1 based on Marlotherm LH (SASOL), the benzyl group is bonded to the ring center to symbolize that it is an isomer mixture. In this isomer mixture, the benzyl group is a toluene residue. To the methyl group (position 1) at the 2-, 3-, or 4-position.

  Marotherm SH (SASOL) is a mixture of dibenzyltoluene. Again, when allocating ring position 1 to the methyl group of the toluene nucleus, both benzyl groups in Marotherm SH (SASOL) are position 2 and 3, position 2 and 4, position 2 and 5, position 2 and 6, position 3 and 4, or at positions 3 and 5. Accordingly, FIG. 2 shows Marotherm SH (SASOL), in which the bond of the benzyl group to the ring center is a mixture of isomers, in which the benzyl group is Connected to the methyl group of the toluene residue (position 1) at positions 2 and 3, positions 2 and 4, positions 2 and 5, positions 2 and 6, positions 3 and 4, or positions 3 and 5.

  More generally, at least 2 substance mixtures utilized as thermal conductors as Marlotherm LH (SASOL) and Marlotherm SH (SASOL) and under other trade names and other trademark owners such as Huels, for example. It can be characterized in that it contains two non-condensed and non-π-conjugated aromatic units. A comprehensive representation of typical structural units in such a mixture is shown in FIG. Typically, 1 to 5 benzyl units are attached to the central aromatic nucleus. Each of these benzyl units can itself again carry additional benzyl units or other alkyl aromatic substituents. In a typical structural unit of a substance commercially used as a heat transfer oil under the trade name Marlotherm LH (Huels) or Marotherm SH (Huels) as a mixture, for example, bonding of a benzyl group and other substituents to the ring center Symbolizes that it is an isomer mixture, in which the benzyl group can be attached at different positions relative to other substituents.

Claims (6)

  In a liquid mixture at room temperature consisting of two or more compounds which are composed solely of carbon and hydrogen elements and constitute a mixture of synthetic substances that can be used as heat transfer liquids in several known compositions, at least Characterized in that it contains at least one compound having two non-condensed and non-pi-conjugated aromatic units and is used in a catalytic process for bonding hydrogen to or liberating hydrogen from the mixture And a mixture.   A method for supplying hydrogen to a consumer at least according to a distribution using the mixture according to claim 1, wherein the reactor is connected to an inlet pipe from a first storage tank for the mixture carrying hydrogen. The mixture fed with the mixture and dehydrogenated in the reactor at high temperature and low pressure is led from the reactor to the second storage tank via the outflow pipe, in which case the reactor is connected via the connecting pipe. Supplying hydrogen to the consumer.   Method according to claim 2, characterized in that the consumer is an internal combustion engine or at least one fuel cell.   4. A method according to claim 2 or 3, characterized in that the consumer contributes to the energy supply of the vehicle.   The mixture contacts the metal-containing catalyst in the reactor to bind or liberate hydrogen, where the metal-containing catalyst used for hydrogen filling and the metal-containing catalyst used for hydrogen release are the same or different. A solid catalyst, in which one or more of the metals palladium, nickel, platinum, iridium, ruthenium, cobalt, rhodium, copper, gold, rhenium, or iron are finely dispersed on a porous, nonpolar support 5. The method according to any one of claims 2 to 4, characterized in that it is contained in a formed form.   Process according to any one of claims 2 to 5, characterized in that hydrogen is liberated in the reactor from a mixture filled with hydrogen by catalytic dehydrogenation at high temperature and low pressure. .

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